W83877ATF Datasheet, PDF (36/191 Pages) Winbond – enhanced version from Winbonds most popular I/O chip W83877F

W83877ATF
2.2.3 Digital Output Register (DO Register) (Write base address + 2)
The Digital Output Register is a write-only register controlling drive motors, drive selection, DRQ/IRQ
enable, and FDC resetting. All the bits in this register are cleared by the MR pin. The bit definitions
are as follows:
7 6 5 4 3 2 1-0
Drive Select: 00 select drive A
01 select drive B
10 select drive C
11 select drive D
Floppy Disk Controller Reset
Active low resets FDC
DMA and INT Enable
Active high enable DRQ/IRQ
Motor Enable A. Motor A on when active high
Motor Enable B. Motor B on when active high
Motor Enable C. Motor C on when active high
Motor Enable D. Motor D on when active high
2.2.4 Tape Drive Register (TD Register) (Read base address + 3)
This register is used to assign a particular drive number to the tape drive support mode of the data
separator. This register also holds the media ID, drive type, and floppy boot drive information of the
floppy disk drive. In normal floppy mode, this register includes only bit 0 and 1. The bit definitions are
as follows:
765 43 ²¹ 0
XX XX X X
Tape sel 0
Tape sel 1
If three mode FDD function is enabled (EN3MODE = 1 in CR9), the bit definitions are as follows:
76 5 4 3 ²¹ 0
Tape Sel 0
Tape Sel 1
Floppy boot drive 0
Floppy boot drive 1
Drive type ID0
Drive type ID1
Media ID0
Media ID1
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Publication Release Date: April 1998
Version 0.51